5.1 Designing a Multi-Channel 4-20mA Analog Input Module
Analog input modules for programmable logic controller continue to enjoy unbroken attention at our customer with the highest growth potential among all other module types. A wide variety of modules with different analog input types, performance-levels, channel densities and safety requirements are available on the market today.
This training helps to understand relevant parameter of a 4-20mA analog input module, such as surge protection, handling miss-wiring, broken wire detection, isolation or protection of the module against over-current at power and signal inputs. First, the proper burden resistor will be selected and different connection options to the high-precision delta-sigma analog-to-digital converter ADS114S08 will be presented. Next, the proper configuration of the ADC will be discussed to achieve maximum resolution at a given sampling rate. Several power tree options are discussed. Finally, all piece are put together to show a possible solution of such a 4-20mA analog input module.